Swimming pool covers are often used for keeping the water free of trash, to shield the water from sunlight that could degrade protective chemicals in the water and for other purposes. Automatic pool covers are often preferable over manually-operated covers, because the cover can be easily extended when the pool is not in use and retracted during use. In most cases, a pool cover box is located at one end of the pool to hold the cover, motor, winding reel and cable.
FIG. 1 shows a generalized schematic of a swimming pool 10 having a pool deck 12 and coping walls 14 surrounding the pool 10. A pool cover 16 extends from a pool cover assembly 18 in a pool cover box 20 disposed at one end of the pool 10. A leading edge bar 22 at the front edge of the pool cover 16 rides in a track encapsulation 24 along the interior walls of the pool 10. Pool cover assembly 18 includes a pool cover motor 21 and a cover wind-up cylinder 26. When the pool 10 is not in use, leading edge bar 22 pulls cover 16 from pool cover box 18 across the length of swimming pool 10. To use the swimming pool 10 the cover 16 is retracted by the pool cover assembly 18 into a cover assembly box 20 causing leading edge bar 22 to also retract into the assembly box 20.
FIG. 2 shows a prior art pool cover assembly 18 and pool cover box 20 in cross-section. A bracket assembly 30 is mounted to the back wall 32 of box 20 to support a lid 34 mounted over a trough 35 in the box 20. A reel 36 is disposed in the trough 35 of box 20 to roll up or unwind the pool cover 16 as it retracts or extends through a space 38.
Prior pool cover boxes have been made in several varieties, such as concrete boxes poured in place or wooden boxes, usually constructed on site. A concrete box is very expensive to make, since it must be formed and poured on location. Also, as a plastic pool cover is extended and retracted relative to the pool and the box, it rubs against parts of the concrete box, wearing the pool cover prematurely. A wooden box is extremely heavy and difficult to maneuver into place. Furthermore, a wooden box tends to deteriorate and warp in the weather, requiring repair and replacement. Metal boxes have also been constructed, but the weight involved makes such boxes cumbersome and expensive.